Cancer Among Those Under 50 Is Rising Dramatically—Study Examines Causes and Risk Factors

The risk of cancer in young adults is rising at an alarming rate—and is expected to keep increasing with every new generation, according to new research.

A study published in Nature Reviews: Clinical Oncology that was focused on changes in the incidence of early-onset cancer globally found that since the 1990s, there has been a significant increase in many types of cancer among those under 50 including breast, colon, esophagus, kidney, liver, and pancreas cancer.

"The younger generation is facing a higher risk for many chronic diseases," Shuji Ojino, MD, PhD, an epidemiologist at Harvard Medical School and Brigham and Women's Hospital who served as senior author of the study, told Health. "Cancer is just the tip of the iceberg."

Indeed, experts say cancer should not be considered a disease impacting only those in middle age or beyond and that cancer prevention is an effort that may need to begin far younger than one might think.

Here's a closer look at the full scope of the study and the steps it suggests to reduce the global burden of cancer and other chronic diseases.

What Is Early-Onset Cancer?

Early onset cancer is any cancer that occurs before the age of 50. According to the American Cancer Society, early cancer is uncommon, and even more so in children and teens.

However, the risk varies depending on the age group. For example, the American Cancer Society says people before the age of 25 have a higher chance of lymphoma, while melanoma cases tend to occur among young women under age 30. Breast, cervical, and colorectal cancer diagnoses are more common after 25.

For the newly published study, researchers from Brigham and Women's Hospital combed through multiple oncology studies from the past decades, spanning back to the 1990s. The researchers focused on the incidence rate of specific types of cancer among young people as well as the risk factors during early life and young adulthood that may explain the rise of these types of cancer. The study defined early life as the moment of conception to 19 years old, marking the end of adolescence.

Researchers found that among people under age 50, there has been a meteoric rise in diagnoses of the following cancers:

• Premenopausal breast cancer
• Colorectal cancer
• Endometrial cancer
• Esophageal cancer
• Head and neck cancer
• Kidney cancer
• Multiple myeloma
• Pancreatic cancer
• Liver cancer
• Prostate cancer
• Stomach cancer
• Thyroid cancer

"Cancer isn't a disease of older individuals" Jack Jacoub, MD, an oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Medical Center, who was not involved in the study, told Health. "Cancer prevention earlier in life may be [the] new normal."

Dr. Jacoub added that the cancers that are increasing in younger individuals tend to be hormone-related cancers such as colorectal cancer, breast cancer, and gynecologic cancers. Historically, he said, doctors are trained to look out for only a handful of cancers like lymphomas and sarcomas that are thought to be more common in young people. Yet, the review suggests that there are a lot more solid tumors that ought to be on a doctor's radar.

What Is the Birth Cohort Effect?

One question the researchers strove to understand was why the rate of cancer diagnoses is increasing. The study points out that the increased incidence of early-onset cancer might be partially linked to more effective screening uptake. However, researchers said other factors may be responsible too.

The "birth cohort effect" was among the additional factors researchers investigated. Researchers observed in the data that people born in the same decade had a higher risk of cancer than in the previous decade. For instance, individuals who were born in 1960 experienced higher cancer risk before they turn 50 than people born in 1950.

Gwendolyn Quinn, PhD, a professor of obstetrics and gynecology and population health at NYU Langone Health, who was not affiliated with the study, explained that each generation lived in the same environmental circumstances, likely fueling a similar risk of disease. Doctors are not entirely sure what specific factors drive the birth cohort effect for contracting cancer, but there are a few leads, Dr. Quinn said.

Genetics, your age, and the time you start your menstrual cycle are some of the uncontrollable factors that may influence cancer risk. However, evidence suggests cancer diagnosis may also be influenced by exposure to certain environmental risk factors that you may have grown up around as a child or teen. Though the study's limitations include not being able to pinpoint what those carcinogenic exposures are.

Emerging lifestyle trends, such as western diets and lifestyles are another factor that appears to be correlated with early-onset cancer.

All of these factors might interact with your genomic or genetic susceptibilities to cancer, said the study. Some of the factors the study says are strongly associated with the increase in multiple types of cancer include:

• Childhood obesity
• High fat "Western" diet and drinking too many sugary drinks
• Lack of physical activity
• Smoking
• Adolescent binge drinking
• Changes in sleep pattern and not meeting sleep guidelines
• Smoking between the ages of 12 and 20
• Exposure to pollution and other airborne carcinogens
• Excess antibiotic use
• Use of birth control pills
• Gut microbiome composition growing up

An alternative explanation for the rising incidence of early-onset cancer diagnoses is the improvements in technology over the years that have led to diagnostic scans that detect cancer soon.

"Oncologists no longer dismiss a young woman with breast lumps as being just cysts associated with menstrual cycles, and these women are sent for mammograms and ultrasounds," explained Dr. Quinn. "The advances in thyroid ultrasound have improved our ability to diagnose early in young people. Any rectal bleeding is further examined rather than assuming it must be hemorrhoids because the person is young."

Another factor contributing to the increase in cancer cases may be growing awareness and openness to discussing cancer in younger populations. The medical community has made strides in being proactive about talking about cancer prevention, such as wearing sunscreen anytime you're outside for over ten minutes, Dr. Quinn said. What's more, people who have a family history of cancer are talking more openly about potential risks, and doctors have been amenable to providing access to early genetic testing, Dr. Quinn added.

Still, it's unknown how much each factor contributes to one's overall risk of cancer. Dr. Ogino's team of epidemiologists is working to answer that question. Their plans include launching a life course cohort study that will involve following kids for decades and keeping track of the food they eat, drink, environment, and more. After 50 years, researchers will compare the upbringing of those kids who eventually developed cancer to those who did not.

What Can Young Adults Do To Reduce or Prevent Cancer Risk?

You can't change your childhood, but making a decision today to live healthier will significantly affect your cancer risk, Dr. Ogino said. Experts recommend not smoking and limiting your drinking to moderate consumption. Regular exercise and maintaining a healthy weight for your height and body will also reduce one's cancer risk.

In addition, adults under 50 should try to follow a plant-based diet as closely as possible, Dr. Jacoub said. Not only can it boost your health to reduce the risk of cancer and heart disease, but he said the diet contains nutrients to enrich your gut microbiome.

Another suggestion is to work on managing your stress. While the relationship is not definitively established, Dr. Jacoub says there is evidence suggesting stress increases inflammatory markers. These markers have been linked to cancer development.

Prevention is key, and that includes regular check-ups and following the ACS guidelines on when you need to get screened. "As we get older into our 20s and 30s, this age group [below 50] don't have the best track record at going to the doctor," adds Dr. Jacoub. "Recognize that some of these things you saw in your grandparents or older relatives are being seen now in young people too."